And with the European minnows unable to respond in a lacklustre second half, Craig Levein's side could still clinch a play-off place.

The win puts the Scots a point ahead of Czech Republic with each having one match remaining.

Playing in a 4-5-1 formation with Mackail-Smith as a lone striker, Scotland started aggressively, gaining three corners in the opening four minutes but failing to capitalise on Charlie Adam's deliveries.

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Interview - Scotland coach Craig Levein

The best chance of the opening stages came on the 10-minute mark, Adam this time delivering from a free-kick 25 yards out to find Steven Naismith. The Rangers striker's flicked header went just wide of goalkeeper Peter Jehle's left-hand post.

Seven minutes later though, Liechtenstein created an equally potent chance at the other end as Thomas Beck played a one-two with Michele Polverino then dribbled past several Scotland players before unleashing a shot from the edge of the box which forced Allan McGregor to parry over the bar.

Naismith had the chance to break the deadlock seconds later when Aston Villa's Barry Bannan set him up just six yards in front of goal, but again his header was ineffectual, this time heading straight into Jehle's hands.

Bannan then found himself in front of goal after a neat set-up from Naismith, his bending ball from the edge of the box going just wide of the post.

Scotland now hope for a positive result in their final fixture against Spain.

The breakthrough came just minutes later though, when Liechtenstein conceded a free-kick 30 yards out which was quickly taken by Phil Bardsley, the Sunderland defender chipping over several Liechtenstein players to find Mackail-Smith, whose looping header sailed past Jehle and into the net for his first international goal.

Three minutes from the break, with the Scots growing further in confidence, Naismith claimed to have been tripped by Martin Stocklasa as he broke in to the box but his pleas were ignored by referee Tom Harald Hagen of Norway.

After the restart, Scotland were keen to extend their advantage with early chances for Mackail-Smith, full-back Alan Hutton and the influential Adam, whose class was evident at both ends of the pitch.

With Liechtenstein's talismanic striker Mario Frick appearing short of match fitness, the side ranked 118th in the world struggled to make inroads, and Frick's lazy back-pass opened up a chance for James Morrison whose half-volley from the edge of the box went wide in the 55th minute.

Scotland continued to show invention as conditions worsened on an already greasy pitch in Vaduz with Christophe Berra also forcing a save from the Liechtenstein goalkeeper, Jehle turning his volleyed attempt from the edge of the box out to concede their sixth corner of the match.

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Interview - Scotland striker Craig Mackail-Smith

Hans-Peter Zaugg's side had few chances in the second half, but Nicolas Hasler was on target with his 69th-minute effort. Picked out by Beck, the Vaduz midfielder forced a second save of the match from McGregor with his low drive towards the right-hand post.

With victory within sight, Bannan and Adam were replaced by James Forrest and Don Cowie for the final quarter of an hour.

By then the pace had slowed, with late chances for Naismith and Berra in the closing stages - Scotland holding out for a crucial victory, but destined to face a stiffer test against world champions Spain on Tuesday, the same night that Czech Republic face Lithuania.